This invention relates to a vehicle position indicating system.
According to the invention there is provided a vehicle position indicating system including a pulse radar transmitter/receiver and a plurality of passive transponders each of which has an antenna coupled to a reflective delay line, different transponders having different delays, the radar and the transponders being arranged for relative movement in respect of each other as a consequence of movement of a vehicle so that passage of a transponder past the radar causes the transmitted radar pulses to be reflected and received at the radar after a time determined by the transponder delay, the radar receiver having a plurality of so-called "range-gates" whereby the received pulses may be classified into time intervals corresponding to the different transponder delays.
In a preferred embodiment of the invention the radar is mounted on a train and the transponders are disposed sequentially at intervals along the track.
The above and other features of the invention will become more apparent from the following description of an embodiment thereof with reference to the accompanying drawings, in which: